Optical properties of a high-efficiency glass ceramic X-ray storage phosphor

摘要

The turbidity, photoluminescence, and photo-stimulated luminescence (PSL) of fluorozirconate glass containing barium chloride nano- and micro-crystals have been measured for samples prepared by isochronal (70 min) annealing over a temperature range of 220-283degreesC, and correlated with the microstructure as determined by X-ray diffraction measurements. Crystallization of hexagonal phase barium chloride commences at around 220degreesC, but until 275degreesC the material retains excellent transparency although it displays negligible PSL. Between 275degreesC and 277degreesC, the hexagonal phase converts to the orthorhombic phase, the transparency abruptly decreases, and the PSL rises to a value of around 13% of that found for the commercial storage phosphor BaFBr:Eu. For a slightly higher temperature of 280degreesC, new phases appear which correspond to the onset of bulk crystallization, and at 283degreesC the relative PSL rises to 33%, while the transparency falls further. The trade-off between optical transparency and PSL over this narrow temperature window for X-ray imaging plate applications is briefly discussed. (C) 2004 Elsevier Ltd. All rights reserved.